Elon Musk, the founder of the SpaceX rocket venture and head of Tesla Motors, heralded the end of his high-profile marriage to British actress Talulah Riley last night with a tragic tweet.

"It was an amazing four years," Musk said in a Twitter update addressed to Riley. "I will love you forever. You will make someone very happy one day."

Musk, 40, and Riley, 26, capped their relationship in 2010 with a storybook wedding in the same Scottish castle where the singer Madonna was married to actor Guy Ritchie. (That marriage also ended in divorce, which could impact Skibo Castle's reputation as a wedding chapel.) Musk was just coming out of a messy divorce from sci-fi novelist Justine Musk, his first wife and the mother of his five children. Riley, meanwhile, was riding high after taking on notable roles in "Pride and Prejudice" and "St. Trinian's."

"We took some time apart for several months to see if absence makes the heart grow fonder, and unfortunately it did not," Elliott quoted Musk as saying. "I still love her, but I’m not in love with her. And I can’t really give her what she wants."

There's been no public reaction from Riley, either in the press or on Twitter.

Beyond the tabloidsNow that we're done with the tabloid angle, I'll just note that Musk has more on his mind than his marital troubles: First, the timing for the demonstration flight of SpaceX's Dragon capsule to the International Space Station is currently in limbo. It had been scheduled for Feb. 7, but this week SpaceX said the launch would be delayed to address "a few areas that will benefit from additional work."

For now, SpaceX isn't specifying exactly which areas of the project could use some additional work, but the launch isn't expected to be delayed more than a couple of months. "We will launch when the vehicle is ready," company spokeswoman Kirstin Brost Grantham said in an emailed statement.

The Dragon's launch on a Falcon 9 rocket would herald a major milestone in the commercialization of orbital spaceflight. The current plan, which has to be cleared not only by NASA but also by the Russians and other space station partners, calls for the unmanned capsule to approach within 1.5 miles (2.5 kilometers) of the orbital outpost, and then go into a holding pattern. If everything checks out, the Dragon would make another approach, stopping just a few yards (meters) from a docking port. Then the station crew would use the robotic arm to pull the capsule in for a docking. After running through tests, the Dragon would undock and head back to an ocean splashdown.

A fully successful test would open the way for commercial cargo flights to the space station, and give a boost to NASA's plans for commercial crew operations sometime in the latter part of this decade.